Effect of antigens from Nippostrongylus brasiliensis and cytokines on the ongoing IgE synthesis in vitro.

The modulation of an ongoing IgE-mediated immune response induced by the infection of mice with the nematode Nippostrongylus brasiliensis (N.b.) was investigated in vitro. In previous experiments antigens derived from the homogenate of adult worms (WH) and third stage larvae (LH) were characterized by immunoblotting. Our results demonstrate that only antigens of the WH were recognized by IgE antibodies. The effect of worm antigens and cytokines (IL-2, IL-4, IL-5, IFN gamma) on the IgE and IgG synthesis in different culture systems was studied. The IgG synthesis of B cells was stimulated by WH or WH/cytokines. The IgE production of B cells was enhanced only by WH/cytokines or when T cells were present. Individual antigen fractions (WH 5, 8, 9, 10, 13) increased the IgE production, which was enhanced in the presence of IL-4 2- to 3.5-fold) but had no significant effects on the IgG production.